Integrated circuits (ICs) are made up of large numbers of semiconductor devices that are interconnected by conductive, usually metallized lines. Such conductive lines will be referred to herein, without limitation, as metallized lines. Several layers of interconnecting metallized lines separated by interlayer dielectric (ILD) layers may be needed to complete all of the necessary circuit connections. Contacts must be formed through the ILD layers at selected locations to allow electrical connections either between metal layers or between a metal layer and a device region in the underlying semiconductor substrate.
In conventional integrated circuit devices the contacts through ILD layers are formed by etching a contact opening through the dielectric material using a photolithographic process. The contact opening is filled by one or more layers of deposited metallic materials. There are many know processes for filling the contact openings. For example, in some applications the contact opening may be filled with a tungsten plug that is formed by depositing sequential layers of titanium, titanium nitride, and tungsten. In other applications, the contact hole may be filled with a layer of tantalum followed by the electrodeposition of a layer of copper.
As ICs become more complex, more and more devices are included on a single semiconductor chip. To accommodate the increasing number of devices, the size of each device and hence the size of each element of a device becomes smaller and smaller. Device size on an IC chip is usually defined by the smallest line or the smallest space between lines that is allowed by the design rules for the chip. Minimum line widths are now in the range of 50 nanometers (nm) or less. As device sizes are reduced, the area allowed for a contact formed through the ILD layers is also reduced. It is becoming increasingly difficult to fabricate such electrical contacts and to insure that the contacts form a reliable connection between device regions.
Accordingly, it is desirable to provide a method for fabricating semiconductor devices having reliable electrical contacts extending through dielectric layers. In addition, it is desirable to provide a semiconductor device that includes a small but reliable contact extending through an ILD layer. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.